docs: def get_emboss_pepstats(self):
          """Run the EMBOSS pepstats program on the protein sequence.
  
          Stores statistics in the ``annotations`` attribute.
          Saves a ``.pepstats`` file of the results where the sequence file is located.
          """
          if not self.sequence_file:
              raise IOError('FASTA file needs to be written for EMBOSS pepstats to be run')
          outfile = ssbio.protein.sequence.properties.residues.emboss_pepstats_on_fasta(infile=self.sequence_path)
          pepstats = ssbio.protein.sequence.properties.residues.emboss_pepstats_parser(outfile)
          self.annotations.update(pepstats)